This gives me a chance to really geek out....Reminds me of the Smallville episode where Clark is playing football and hurts a member of the other team when Mr. Mytzplikt (whatever?) jinxes him and causes him to trip.
Clark and Pa Kent get into a big arguement and Clark notes that he has always had to use extreme caution in every situation (handshakes, hugs, etc...).
As an aside, we find out in All-Star Superman #2 that Supes is able to lift 100's of millions of tons. The key to the Fortress of Solitude weighs a 1/2-million tons itself.
I think it's a matter of "power control" learned over time.
All that being said, I cannot see the Hulk having the patience for sewing.
Ahhh, that felt good.
Good point. Though, as far as the Hulk sewing.. I think it would depend on who's writing him. If Peter David is writing then Hulk might do it just to [embarrassing lack of self control] off Bruce. . But I agree. Learned control. Look at IH #82 when Hulk was beating up his gray version. "You don't get it. You are what I was. I'm a lot more now." Something to that effect. Smart Hulk can think and reason and can control his power.